bpo-29418: Implement inspect.ismethodwrapper and fix inspect.isroutine for cases where methodwrapper is given (GH-19261)

Automerge-Triggered-By: GH:isidentical

Doc/library/inspect.rst

@@ -429,6 +429,14 @@ attributes:
    Return ``True`` if the object is a built-in function or a bound built-in method.
 
 
+.. function:: ismethodwrapper(object)
+
+   Return ``True`` if the type of object is a :class:`~types.MethodWrapperType`.
+
+   These are instances of :class:`~types.MethodWrapperType`, such as :meth:`~object().__str__`,
+   :meth:`~object().__eq__` and :meth:`~object().__repr__`
+
+
 .. function:: isroutine(object)
 
    Return ``True`` if the object is a user-defined or built-in function or method.

Lib/inspect.py

@@ -121,6 +121,7 @@ __all__ = [
     "ismemberdescriptor",
     "ismethod",
     "ismethoddescriptor",
+    "ismethodwrapper",
     "ismodule",
     "isroutine",
     "istraceback",
@@ -509,12 +510,17 @@ def isbuiltin(object):
         __self__        instance to which a method is bound, or None"""
     return isinstance(object, types.BuiltinFunctionType)
 
+def ismethodwrapper(object):
+    """Return true if the object is a method wrapper."""
+    return isinstance(object, types.MethodWrapperType)
+
 def isroutine(object):
     """Return true if the object is any kind of function or method."""
     return (isbuiltin(object)
             or isfunction(object)
             or ismethod(object)
-            or ismethoddescriptor(object))
+            or ismethoddescriptor(object)
+            or ismethodwrapper(object))
 
 def isabstract(object):
     """Return true if the object is an abstract base class (ABC)."""
@@ -1887,13 +1893,9 @@ def getcoroutinelocals(coroutine):
 ###############################################################################
 
 
-_WrapperDescriptor = type(type.__call__)
-_MethodWrapper = type(all.__call__)
-_ClassMethodWrapper = type(int.__dict__['from_bytes'])
-
-_NonUserDefinedCallables = (_WrapperDescriptor,
-                            _MethodWrapper,
-                            _ClassMethodWrapper,
+_NonUserDefinedCallables = (types.WrapperDescriptorType,
+                            types.MethodWrapperType,
+                            types.ClassMethodDescriptorType,
                             types.BuiltinFunctionType)
 
 
@@ -2533,7 +2535,7 @@ def _signature_from_callable(obj, *,
     elif not isinstance(obj, _NonUserDefinedCallables):
         # An object with __call__
         # We also check that the 'obj' is not an instance of
-        # _WrapperDescriptor or _MethodWrapper to avoid
+        # types.WrapperDescriptorType or types.MethodWrapperType to avoid
         # infinite recursion (and even potential segfault)
         call = _signature_get_user_defined_method(type(obj), '__call__')
         if call is not None:

Lib/test/test_inspect.py

@@ -44,7 +44,8 @@ from test.test_import import _ready_to_import
 # isbuiltin, isroutine, isgenerator, isgeneratorfunction, getmembers,
 # getdoc, getfile, getmodule, getsourcefile, getcomments, getsource,
 # getclasstree, getargvalues, formatargvalues,
-# currentframe, stack, trace, isdatadescriptor
+# currentframe, stack, trace, isdatadescriptor,
+# ismethodwrapper
 
 # NOTE: There are some additional tests relating to interaction with
 #       zipimport in the test_zipimport_support test module.
@@ -93,7 +94,8 @@ class IsTestBase(unittest.TestCase):
                       inspect.ismodule, inspect.istraceback,
                       inspect.isgenerator, inspect.isgeneratorfunction,
                       inspect.iscoroutine, inspect.iscoroutinefunction,
-                      inspect.isasyncgen, inspect.isasyncgenfunction])
+                      inspect.isasyncgen, inspect.isasyncgenfunction,
+                      inspect.ismethodwrapper])
 
     def istest(self, predicate, exp):
         obj = eval(exp)
@@ -169,6 +171,14 @@ class TestPredicates(IsTestBase):
             self.istest(inspect.ismemberdescriptor, 'datetime.timedelta.days')
         else:
             self.assertFalse(inspect.ismemberdescriptor(datetime.timedelta.days))
+        self.istest(inspect.ismethodwrapper, "object().__str__")
+        self.istest(inspect.ismethodwrapper, "object().__eq__")
+        self.istest(inspect.ismethodwrapper, "object().__repr__")
+        self.assertFalse(inspect.ismethodwrapper(type))
+        self.assertFalse(inspect.ismethodwrapper(int))
+        self.assertFalse(inspect.ismethodwrapper(type("AnyClass", (), {})))
+
+
 
     def test_iscoroutine(self):
         async_gen_coro = async_generator_function_example(1)
@@ -241,8 +251,38 @@ class TestPredicates(IsTestBase):
         coro.close(); gen_coro.close() # silence warnings
 
     def test_isroutine(self):
-        self.assertTrue(inspect.isroutine(mod.spam))
+        # method
+        self.assertTrue(inspect.isroutine(git.argue))
+        self.assertTrue(inspect.isroutine(mod.custom_method))
         self.assertTrue(inspect.isroutine([].count))
+        # function
+        self.assertTrue(inspect.isroutine(mod.spam))
+        self.assertTrue(inspect.isroutine(mod.StupidGit.abuse))
+        # slot-wrapper
+        self.assertTrue(inspect.isroutine(object.__init__))
+        self.assertTrue(inspect.isroutine(object.__str__))
+        self.assertTrue(inspect.isroutine(object.__lt__))
+        self.assertTrue(inspect.isroutine(int.__lt__))
+        # method-wrapper
+        self.assertTrue(inspect.isroutine(object().__init__))
+        self.assertTrue(inspect.isroutine(object().__str__))
+        self.assertTrue(inspect.isroutine(object().__lt__))
+        self.assertTrue(inspect.isroutine((42).__lt__))
+        # method-descriptor
+        self.assertTrue(inspect.isroutine(str.join))
+        self.assertTrue(inspect.isroutine(list.append))
+        self.assertTrue(inspect.isroutine(''.join))
+        self.assertTrue(inspect.isroutine([].append))
+        # object
+        self.assertFalse(inspect.isroutine(object))
+        self.assertFalse(inspect.isroutine(object()))
+        self.assertFalse(inspect.isroutine(str()))
+        # module
+        self.assertFalse(inspect.isroutine(mod))
+        # type
+        self.assertFalse(inspect.isroutine(type))
+        self.assertFalse(inspect.isroutine(int))
+        self.assertFalse(inspect.isroutine(type('some_class', (), {})))
 
     def test_isclass(self):
         self.istest(inspect.isclass, 'mod.StupidGit')

Misc/NEWS.d/next/Library/2020-03-31-20-53-11.bpo-29418.8Qa9cQ.rst

@@ -0,0 +1 @@
+Implement :func:`inspect.ismethodwrapper` and fix :func:`inspect.isroutine` for cases where methodwrapper is given. Patch by Hakan Çelik.